This may sound harsh, but really, a Party Planner for a one year old's birhtday? One year old children really don't have "friends" in the true sense because they haven't developed social skills yet, so the party is really for the adults. Instead of attempting an event, why not shoot for creating a memory for your family. It doesn't need to be extravagent or complicated. You have a great excuse to get people you care about together. Invite family and close friends. Include other one year olds and their parents if you're in a mommies group and have close ties with those moms.
Since the weather has been warm, why not a BBQ at your home or a local park. Take along some frisbees, beach balls, etc. for fun. If older children will be present, rent a jumping unit. They cost $100-$150 depending on the size and shape. The company you rent from handles setting theunit up and taking it down. I'm sure they have things like castles and such for little girls. Even adults like these things, in fact at our grandson's party last year, there were as many adults jumping as there were kids.
If you want entertainment, consider a clown who makes balloon animals and stuff. Or perhaps someone who puts on children's puppet shows.
Have a pretty birthday cake, 2 in fact. I always made a separate cake for my children and grandchildren on their first birthday. If she like a particular character, Winnie the Pooh, Big Bird, etc., you can check with a place like the Cake Works in San Jose to find someone who makes them if you don't bake yourself. Or have your favorite bakery make something appropriate and to your liking. The Birthday child's cake, I've always made in a small 6"-7" size. It is their cake. Make sure her clothes are protected or better yet, strip her down to a diaper. We put the Birthday child in a high chair, put the cake on the eating tray, and let them at it (that's why the small cake). Her little hands will probably be in it first, followed by a few bites into the frosting edges. Our chilren never ate more than a few bites, but ended up with cake and frosting all over themselves, much to the delight of the adults at our parties. The cake becomes a messy plaything.
Take movies of the day and lots of pictures.
To this day, the Birthday Party movies are my adult children's favorites. I've always gone with the KIS (keep it simple)principle and it's always worked well without going overboard and breaking the bank. I've watched some of our neighbors go overboard with rented horse rides, traveling circuses, etc. They spent a lot of money and the children lost interest quickly and didn't really appreciate the entertainment provided.
Good Luck with you 1st party. I hope some of these ideas help you.
L.